Complacency is the likely reason for Singapore's litter woes. Experts say that when people know there will be an army of cleaners to pick up after them, they become too lazy to do the right thing.
Singapore residents and Members of Parliament offer reasons why people do not clean up after themselves:
Coddled by cleaners
With cleaners out every day to sweep up trash, many people have developed the mindset that there is always someone, somewhere, to pick up after them.
Mr Lee Yong Se, 32, who works in the social sector, said that in countries like Japan, citizens are forced to clean up after themselves owing to a lack of cleaning staff. "Here, the expectations are different. People expect to find other people to clean up after them."
As of last September, there were 52,000 cleaners here, of which 38,000 - or about two in three - were Singaporeans or permanent residents, said the National Environment Agency (NEA).
Different cultural attitudes
New citizens and foreign workers may come from countries where keeping public spaces clean is not the norm.
About 19,000 tickets for littering were issued by the NEA last year, of which 31 per cent were given to non-residents.
"Some may not be attuned to our spirit of not littering, so you need to educate (them)," said Nee Soon GRC MP Lee Bee Wah, whose constituency holds a No Cleaners Day to get residents to pick up trash.
"The majority of us don't litter... it's just that we have these new social dynamics, so we need to keep pushing hard."
Mr Lawrence Loh, 65, a retired executive vice-president of marketing, agreed. "Some of them are from countries where there is no clampdown on littering, and they have the use-and-throw mentality," he said.
Because they can
In an NEA study done from 2009 to 2010, four out of 10 people in Singapore said they would litter out of convenience or if they knew they could get away with it.
"People litter because they don't care, and they don't care because they don't get caught," said bank analyst Jason Ng, 24.
National University of Singapore sociologist Paulin Straughan said there are those who litter to test their boundaries.
"These are the ones who would likely not break the rules if there were law enforcement officers right in front of them," she said.
Associate Professor Straughan, who led the NEA study, added that a very small minority is made up of people who are anti-establishment, very much like those of deviant sub-cultures.
"They find they cannot identify with the main group, the norms, and so they set their own rules," she said.
'That's not littering'
Everyone knows flicking a cigarette butt onto the floor or hurling a used nappy out of the window is littering.
But some Singaporeans have found their own way to justify their anti-social actions.
"If the litter bin is full and if you put trash around it, it is littering, but people will say no, (it is not)," said Prof Straughan.
The NEA study also found that about two in 10 people did not think they were littering if their serviettes blew away in the wind. Three out of 10 thought leaving rubbish on a park table after a barbecue was also not littering.
Too lenient now
"We have become reluctant to do the bad thing," said Mr Liak Teng Lit, chairman of the Public Hygiene Council, referring to enforcement, including fines and Corrective Work Orders (CWOs), and speaking up when one sees others littering.
Enforcement was more thorough in the 1970s to early 1990s, said Mr Liak, when photos of people queueing up to pay their littering fines were published.
When CWOs were introduced in 1992, offenders made to clean public areas did so under the glare of the media. Photos of them carrying out CWOs were splashed in the newspapers.
"Over the years, we have become more forgiving, with more emphasis now placed on education," said Mr Liak.